Just want to ask about my power meter accuracy coming from zpower

(Gem Lacson) #1

Recently, just got my power meter (Powerbeat G3) one sided.

I started zwifting using zpower, from 208 FTP to 253 FTP (not doing FTP test but climbing Alpe Du Zwift only). Then when I got my power meter, followed every instruction. Also calibrated before every ride and in some races after my warm-up. Also emailed the company of power meter because the starting setting is offset to -10% which I switched immedietly to 0 offset.

First race got 285 FTP and still able to sprint at the end, won the race. Next group ride it rose to 305 FTP because I chased hard the break.

Wondering if that would be true (accurate), because from 255 (zpower), my ftp now in power meter is 305. I also tend to tighten a little bit more my rear wheel when using zpower because I want to train harder before getting my power meter but the jump on ftp is big.

P.S. I did my 285/305 FTP race/rise hitting 193 max HR which I think would support the effort.

(lukas ranicar) #2

congratulations! powermeter is more accurate than zpower.

(Evert Herremans) #3


Your power meter should be more accurate then zpower, if it’s correctly calibrated (which is most likely the case). I have to ask though: have you ever done a proper FTP test? I know Zwift sometimes comes and tell you, “hey it looks like your FTP increased to xxx”, after a random ride but these values are always off. The only correct way to determine your FTP is by doing an isolated test. Either the standard 20min test that’s already in Zwift. Or you could use this ramp test:

There’s only a few trainers on the market where zpower is meaningful. The Kinetic Road Machine for example is a fluid trainer where resistance goes up the faster your wheel spins. Zwift knows approximately how much power your putting out when your wheel is spinning 20 - 25 or 30kph. Any trainer however that has a hand switch to increase/decrease resistance is useless when you wanna use zpower.

Kind regards

(Gem Lacson) #4

I did do a FTP test, 20 mins. Got my starting FTP for zpower at 208. Improved then to 253 as Zwift suggests “hey…” with a ride, still in zpower. And power meter rides improved it now to 305 again as Zwift suggests only "hey…). I didnt do a FTP test again yet, its hard, but I made a schedule to do it on December after my training plan, it was my goal to increase more my ftp.

For trainer, using Jetblack Z1 fluid pro.

(Gem Lacson) #5

Thanks lukas, I think so it is accurate because its very consistent. I was just shocked of the improvement on my FTP as zwift suggests.

(Daren Chandisingh [Vision]) #6

#humblebrag :smiley: Congratulations! As already said, your power meter should be giving you a more accurate result, so I’d be more inclined to think your zPower results were lower than they should be.

(Which itself is ironic since many people complain about the assumed zPower advantage with over-estimated power.)

(Gerrie Delport) #7

@Daren_Chandisingh: People only say Zpower over-estimate if they get beaten by a Zpower rider … LOL